package edu.chen.dao;


import edu.chen.bean.User;

public interface UserDao {
    /**
     * add a new User
     * @param user
     */
    void insert(User user);

    /**
     * delete a User
     * @param username
     */
    void delete(String username);


    /**
     * query a User
     * returns an instance if it exists
     * else return null
     * @param username
     * @return
     */
    User query(String username);
    


}
